^^6 VASCULAR CRYPTOGAMS. 



Lycopodiacece, the prothallium is developed in the spore itself, filling it up with 

 a mass of tissue, the archegonia becoming exposed only by the splitting of the 

 cell-wall of the spore. The microspores of this section produce the antherozoids 

 after a previous endogenous formation of cells, which must be regarded as a rudi- 

 mentary prothallium. 



The Archegojtia of Vascular Cryptogams are, like those of the Muscineae, 

 masses of tissue, consisting of a ventral part which encloses the oosphere, and of a 

 neck, usually short and composed of four longitudinal rows. The two groups 

 differ in the fact that in Vascular Cryptogams the tissue of the wall of the 

 ventral part is formed from the prothallium itself; and the ventral part of the 

 archegonium is therefore enclosed in the tissue of the sexual generation, the neck 

 only projecting beyond it. The neck and central cell arise from an epidermal 

 cell of the prothallum ; the protoplasm of the central cell divides in this case also 

 into two unequal portions ; the lower larger one becomes by rejuvenescence the 

 oosphere, while the upper small portion, the canal-cell, penetrates between the 

 rows of cells of the neck and becomes converted into mucilage (after having, in 

 the case of Ferns, produced, according to Strasburger, at least an indication of an 

 axial row of cells). The mucilage thus produced in the neck finally swells up 

 considerably, drives apart the four apical cells of the neck, and is expelled; an 

 open canal is thus formed, leading from without to the oosphere ; the expelled 

 mucilage appears to play an important part in the conduction of the ' swarming' 

 antherozoids to the opening of the neck. FertiHsation is always effected by means 

 of water, which determines the opening of the antheridia and archegonia, and 

 serves as a vehicle for the antherozoids. The advance of these latter as far as the 

 oosphere, and even their entrance into and coalescence with its protoplasm, has 

 been directly observed in the different groups. 



The Antherozoids are, like those of the IMuscinese, spirally coiled threads usually 

 wdth a number of fine cilia on the anterior coils. In the cases hitherto observed they 

 arise from the peripheral part of the protoplasm of their small mother-cells, a central 

 vesicle of protoplasm, containing starch-grains, remaining behind, which, adhering 

 to a posterior coil of the antherozoid, is often dragged along by it, but is detached 

 before its entry into the archegonium. The mother-cells of the antherozoids arise, 

 in Ferns and Equisetacese, in the antheridia, which project free from the prothallium 

 as roundish masses of tissue ; but in the Ophioglossacese are imbedded in the pro- 

 thallium. Among Rhizocarpeae, Salvinia forms a very simple antheridium proceeding 

 from the microspore, while the IMarsileaceae and Selaginelleae produce their anthero- 

 zoids within the microspore itself; but in the latter only after a few-celled mass of 

 tissue has been formed in it which must be considered as a rudimentary prothallium 

 (Millardet). 



The Asexual Generation which produces Spores arises from the oospore 

 or fertilised oosphere in the archegonium. In Ferns, Equisetaceae, and Rhizo- 

 carpeae, its earliest divisions, the rudiments of the first root, the first leaf, and the 

 apex of the stem, can be recognised, while at the same time a lateral outgrowth of 

 its tissue, called the Foot, commences at the bottom of the ventral part of the arche- 

 gonium, and draws from the prothallium the first nourishment for the young plant. 

 The ventral part of the archegonium at first grows vigorously (except apparently 



